Carburetor



Noy.4,1941.- H. A. CARLSON ETAL 2,261,794

cmaunmpn Filed Oct. 28, 1938 4 Sheets-Sheet 1 FIG. 3

INVENTORS HAROLD A i CARLSOB ALEX N. SzwmsuLsK I BY ATTORNEY.

Nov. 4, 1941.

H. A. CARLSQN ET AL CARBURE'IOR Filed Oct. 28. 1938 4 Sheets-Sheet 2 INVENTORS HAROLD ALCARLSON NQ'SZWARGULSKI ALEX KTTORNEY Nov. 4, 1941. H. A. CARLSON EI'AL CARE- *ti on Filed Oct. 28, 1938 4 Sheets-Sheet 3 FIG. 10'.

INVENI'ORS HAROLD A. CARLSON v ALEX N, SZWARGULSN 4% I ATTORNEY Nov. 4, 1941.

H. A. CARLSON Er AL 2,261,794

CARBURETOR Filed Oct'. 2a, 1938 4 Sheets-Sheet 4 i 3 p FIG-l1. 7

I I: a 1 HI! NW "Hi E lNVEN ORS HAROLD A. CARL$YON ALEX N. SZWARGULSKI ATTORNEY Patented Nov. 4, i941 UNITED STATES PATENT orr cs 2.261.794 cannunn'ron Harold A. Carlson, University City, and Alex N. Szwargulski, St. Louis, Mo., assignors to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application October 28, 1938, Serial No. 237,454

Claims. (Cl. 261-41) nozzle, so that greater depression must be produced at the mouth of the nozzle than would otherwise be necessary to draw fuel therefrom. In order to cause the main fuel nozzle to discharge at lower suctions, independent main and idling supply systems have been suggested, but these require some means for cutting out or substantially decreasing the idling discharge when the main nozzle /starts to function, as without such means, the carburetor will flow excessively rich during the part throttle range with both the main and idling systems discharging.

It is an object of the present invention to provide novel means for restricting the idling discharge when the throttle valve is opened far enough, duringnormal operation, to insure a discharge from the main nozzle.

Another object is to provide for a dischargeof maximum richness from the idling port during the cranking and warm up periods when the choke valve is closed or only partially opened.

A more detailed object is'to provide a throttle controlled device for closing of! the connection between the idling .system and the main fuel reservoir when the throttle valve has been opened to a predetermined extent.

Another detailed object. is to provide an idling system having air vent means with valves conthe suction applied through the idling passages tends to hold back the discharge from the main Fig. 3 is an enlarged perspective view showing a detail of the metering pin operating structure in Figs. 1 and 4.

Fig. 4 is a section through the float bowl and fuel metering mechanism of Fig. l and is taken at 90 thereto, certain parts being moved into the section plane for clearer illustration.

Fig. 5 is a view similar to Fig. 4 but showing the fuel metering valve open.

Fig. 6 is an enlarged detail view of the structure in Figs. 1 and 4 showing the main metering pin connection to the accelerating pump lever.

trolled by the choke and throttle valves in a manner to render the idling system more effective for discharging fuel when either orboth valves are closed than when the valves are at least partially opened.

These objects and other more detailed objects hereafter appearing are attained substantially by the devices illustrated in the accompanying drawings in which- Fig. 1 is a side view and longitudinal section showing a carburetor embodying one form of the invention and is taken substantially on line l-l of Fig. 4.

Fig.2 is an enlarged partial section taken on' line 2--2 of Fig. 4.

Fig. 7 is a ,view corresponding to Fig. 4 but.

showing a second form of the invention.

Fig. 8 is aside view shown partially in section on line 8-8 of Fig. 7, parts being omitted.

Fig. 9 is a side view andsection corresponding to Figs. 4 and '7, but-showing a third form of the invention.

Fig. 10 is an enlarged view showing a detail of the structure in Fig. 9, the air valve and ope erating arm being shown in different positions.

Fig. 11 is a side view and section showing a \earburetor embodying a fourth form of the invention.

Figs. 12 and 13 are enlarged detailviews showing a portion of the structure in Fig. 11, the throttle operated air valve being shown in different positions.

Fig. 14 is an enlarged view showing the valve forming end of the throttle shaft in Fig. 9.

In the accompanying drawings, like numerals indicate like parts in" the various forms. The

- carburetor in Figs. 1-6, inclusive, has a downdraft mixture conduit including an air inlet horn I, venturis 2 and an outlet portion .3 flanged as at 4 for attachment to the intake manifold (not shown) of an associated internal combustion engine. An unbalanced choke valve 5 is mounted on shaft 6 in the air inlet horn and a throttle valve 1 is mounted on shaft ii in the outlet portion. The choke valve is automatically I controlled by thermostatic mechanism in housing A or may be manually controlled. Adjacent the mixture conduit is a bowl 9 within which m1 is maintained at a substantially constant level by the usual needle valve and float mechanism (not shown). Fuel is supplied to the mixture .conduit through a main nozzle Ill and idling system including passages I], I2 and I3 discharging through a port 14 adjacent and, posterior to the edge of the throttle valve when closed. Idling passage I2 is provided with an air bleed port Ila opening into the mixture conduit.

Main nozzle ll communicates with the fuel bowl through a calibrated metering orifice element l6 which is variably restricted by a stepped metering rod l6 carried at its upper end by rocker lever l1 pivotally mounted on post It projecting above the bowl cover. Lever l1 at one end is connected to the throttle valve by means of a link I 9 and crank 26 rigid with the throttle shaft and at the other end is connected by means of a. link 2| to fuel pump piston rod 22. Rod 16 has an enlargement 23 near its lower extremity arranged to seat on and close metering element l6 when l the throttle valve is closed. A spring 26,;interposed between arm i1 and rod l6, (Fig. 6) provides for yielding connection of lever l1 and metering rod l6.

The idling system communicates with the fuel bowl an orifice 26 which connects with idling passage II by means of a cross passage 21. A calibrated metering tube 26 is mounted in'passage i l. Associated with port 26 is a valve 29 normally urged upwardly towards its closed position by a coiled spring'36 seated upon a threaded plug 3|. A rod 32 projects upwardly from valve 26 through port 26 and through the top of the fuel bowl and has a cross piece 33 at its upper extremity. A lug 36 projects from pump rocker lever l1 in position to engage cross piece 33 when the throttle valve is substantially closed to forcerod 32 downwardly and open valve 29.

Pivotally supported at 36, on the outer wall of the carburetor air hom portion is a bell crank lever 31 (see Fig. 3) having laterally projecting lugs 38 and 39 at its extremities. Choke shaft 6 projects slightly beyond the wall of the air'horn idling system to the fuel bowl when either the choke or throttle is closed. The trottle control is arranged to permit closing of valve 29 under the influence of spring 36 when the throttle valve is opened sufilciently to cause a discharge from the main fuel nozzle under normal operating conditions, thus cutting of! fuel supplied to the idling system and, in effect, increasing to infinity the ratio of air to'f uel in the discharge from the idling system. The choke valve control may be arranged to hold the valve open only when the choke valve is fully closed, in order to provide a rich starting mixture, or valve 26- snay be held open during any desired portion of the choke opening movement.

In Figstj and 8, rod 32a and valve 26a are provided with a longitudinal v: e as at 62 to provide a constant feedto the idling s less of the position of valve 26a. In thisform. valve 29a iscontrolled from the pump rocker arm as in the previous form. An additional fuel feed to the idling system is provided at 63, this orifice communicating with idling passage II by means .of passages 66 and 66, the former being formed .on the inner wall of the fuel bowl.

passage 66 forms a continuation of passage 66 as at 61. Choke shaft 6a extends intopassage- 66 and is slotted to form a valve structure 66.

tem regard-.

A vertical 7 valve structure 16. Theslot in valve structure the idling system which is controlled by valve structure 66. This vent is, preferably, of sumcient capacity relative to the smallest section of idling passages 66', ll, l2 and -I3 and port l6 to 6 eifectively prevent the drawing of idling fuel through orifice 63 and restriction 66, when the choke valve is opened aligning slot 66 with passage 66. The idling system is thereafter fed .through orifice 26 until the throttle valve is opened sufllciently to-permit closing of valve 26a.

When valve 29a is closed, a restricted fuel discharge through the idling system may be obtained by means of by-pass 62, where such discharge is required to obtain the proper mixture 16 proportions, particularly during part throttle operation. In this form, as in the first form, .means is provided for substantially restricting the discharge through the idling system when the choke and throttle valves are at least partially opened, an idling fuel discharge of maximum richness being provided when both the choke and throttle valves are substantially closed. In starting a cold engine, the choke will be closed and the throttle partly open permitting the feeding of zaruel through port 63 and the idling system.

In the third form in Figs. 9 audio, the idling system communicates with the fuel bowl through a calibrated tube 66, passages 6|, 62 and 63 forming an air vent into the interior of the air horn.

The end of choke shaft 6b extends into passage 62 and is slotted to form a valve structure 660. A rocker lever Ila is pivotally supported above the fuel bowl and connected at one end to the throttle valve, as in Figs. 4 and 7, by means of link l9 and arm 26, and has holes 66 at its opposite end for connection to the fuel pump piston rod (not shown). The intermediate portion of rocker lever 66 is shaped to form a cam as at 66. Interposed in passage 6| is a valve 61 normally urged upwardly towards its closed position by a 5 the main nozzle under normal operating conditions, to open valve 61. when the throttle valve is substantially closed, cam 66 permits closing of valve 61 by spring 66 to cut'oif the air bleed. Preferably the vent is of suilicient capacity to eifectually prevent discharge through the idling system when both the choke and-throttle valve are at least partially opened, although, if desired, a limiteddischarge through the idling system may be maintained where this is necessary to obtain a desired part throttle mixture quality curve.

In the fourth form in Figs. 11-14, which is very similar tothe third form, the idling system is formed by passages. 66-, 66 and 61 communicating with the fuel bowl through orifice 66 and discharging adjacent the-edge of the throttle valve,

when closed, by means of port 66. Passages 16, 1|, 12 and 13 form an air vent for the idling system communicating with the atmosphere as at 16. Choke shaft 6b extends into passage 1| and is slotted to form a valve structure 660, as in the previous form. The end of the throttle shaft extends into passage 13 and is cut out to form 6641 is arranged to align with e 1| when the choke valve is open. Solid portions-16 in valve structure 16 register with passage 13 when the throttle-valve is substantially closed, and,

Passages 66 and 61 constitute an air vent forwhen the throttle valve is opened'far enough to of said throttle.

permit discharge'from the main noz zle under normal'operating conditions, these solidportions are in position as to open the vent. Thus, when both the choke and throttle valves are at least partially open, the air vent will be open so as to substantially increase the ratioof airto fuel inthe idling discharge. Figs. 12 and 13 show the throttle valve structure 15 in various positions relative to passage 13.

The arrangement of the carburetor in general as well as the various fuel .supply passages is not essential and these may be modified as desired. .The invention is particularly adaptable to carburetors having independent idling systems, but features thereof may be utilized to ad-" vantage in carburetors having the interconnected. idle and main fuel systems, in the latter case, it

being important that the fuel valve control an efiective metering restriction in the idling system,

since, ordinarily, the -main* metering elements which control the main nozzle discharge are inefiective as control means for the idling mixture.

The exclusive use of all such modifications as come within the scope of the appended claims is contemplated.

We claim: 1. In a carburetor, a mixture conduit, a fuel reservoir, a throttle, and a choke in said conduit, main and idling fuel passages discharging into said conduit, respectively, anterior and pos- .terior to said throttle when closed, said idling passage communicating with said reservoir independently of said main fuel passage and having ports for supplying a mixtureflof fuel, and air thereto, valve means cooperating with at least one of said ports for controlling the supplyof fuel and airthrough said ports, valve actuating means urging said valve means toward a position to cause the supplying of a relatively lean mixture through said idling passage, throttle operated mechanismfor shifting said valve 'means toward the opposite position to cause the supplywhen either saidchoke valve or said throttle valve approaches its closed position.

3. In a carburetor, a fuel reservoir, a mixture;

conduit, a throttle anda choke in said conduit,

an idling passage communicating with said reser.-' voir below the fuel level and discharging into said conduit on both sidesof said throttle when closed, air bleed port means in the wall of said idling passage, valve :means controlling said-port means, 'and mechanism including. independent operative connections between saidchoke and throttle and-said valve means for closing said valve meanswhen either said choke or throttle approaches itsclosed. position and for opening saidvalve means when both said choke-and throttle are substantially opened. 4. In a carburetor, a fuel reservoir, a mixture conduit, 5 throttle and a choke in said conduit,'

an idling passage communicating with said reservoir -below the fuel level and discharging into said conduit'onboth sides of said throttle when closed, there being ports in said idling passage for admitting liquid fuel and air thereto, valves controlling said ports, mechanism including an operative connection between said throttle and one of said valves for shifting said last mentioned valve, when said throttle approaches its closed position, to a position for supplying a relatively rich mixture through said idling passage and for shifting said last mentioned valve toward its opposite position to decrease the proportion of fuel inv the mixture supplied. through said idling passage when said throttle is substantially opened, and an operative connection between said choke and the other of said valves for shift- I ing the same to a position to supply a relatively ing of a relatively rich mixture through said idling passage, when said throttle approaches its closed position, and valve actuating means operated by said choke for shifting said valve means toward said opposite position when'said choke is substantially closed irrespective of the position 2. In a carburetor, a fuel reservoir, a mixture.

. reservoir belowthe' fuel 'levelanddischarging into said conduit'on both sides of --said throttle valve when closed, a valve means for varyingthe conduit, throttle and choke valves in said conduit, an idling passage communicating with said reservoir below: the fuel level" and discharging into said conduit on both sides of said-throttle valve when closed, a fuel control valve in said idling passage, means for impositively closing said fuel;

control valve, andindependent operativefcon- .nections between said choke and throttle valves and said fuel control valve to force said fuel control valve open against said impositive means rich mixture through said idling passage when said chokeapproaches closed position and toward its opposite position for decreasing the proportion of fuel in the mixture supplied through said i f idling passage when said chokeis substantially opened.

5 In a carburetor, a fuel reservoir, a. mixture conduit, throttle and choke valves in said conduit, an idling passage communicating with said rate of fuelflow through the .idling passage,

HAROLD A, oAR SoNQ ALEX N. .szwanoursxr. 

